A relay device of an inner cable disclosed in Patent Literature 1 is known as a device including a fitting member for fitting a long member such as an inner cable therein. As illustrated in FIGS. 7(a) and 7(b), a relay device 100 disclosed in Patent Literature 1 includes a tubular casing 101, cap members 102a and 102b attached respectively to front and rear ends of the casing 101, a joint piece 103 that is slidable in the casing 101, a first inner cable 104 engaged with a front part (the left side of FIGS. 7(a) and 7(b)) of the joint piece 103, and a second inner cable 105 engaged with a rear part (the right side of FIGS. 7(a) and 7(b)) of the joint piece 103 in a manner that the second inner cable 105 can be freely engaged with and removed from the rear part. The relay device 100 is configured such that the casing 101 includes a cover piece 101a that is a part of a peripheral wall from near the center to the front end, the part being attachable and detachable, and the joint piece 103 can be removed from inside the casing 101 by removing the cover piece 101a. 
The joint piece 103 includes a first engaging portion 103a in which a hole is formed to engage the first inner cable 104. The first inner cable 104 is inserted through the hole of the first engaging portion 103a. A first cable end 104a is swaged and fixed to a distal end of the first inner cable 104. The first cable end 104a is engaged with the front part of the joint piece 103 in the joint piece 103. Meanwhile, a cylindrical second cable end 105a is fixed by casting to a distal end of the second inner cable 105. The second cable end 105a includes a spring piece 105b expanding outward. The second cable end 105a including the spring piece 105b is inserted into a ring-shaped second engaging portion 103b of the joint piece 103 from the rear side thereof. Consequently, the second inner cable 105 is attached to the joint piece 103.